Fiber optics (FOs) are imaging devices formed by bundling and integrating a plurality of fibers that propagate light, and have been used as, for example, optical waveguides of optical instruments such as image intensifiers, faceplates of CRTs, and CCD couplings.
In such FOs, there has been known a configuration for preventing degradation in resolution and noise generation by preventing light (stray light) leaking from a fiber propagating light from entering another fiber. Examples thereof include a configuration of interposing an absorber between the cores to absorb stray light.
Such an absorber contains an oxide colorant, and the oxide colorant determines absorption characteristics of the absorber. For example, it has been known that absorption characteristics of the absorber in the visible light region become satisfactory when Fe2O3 is used as an oxide colorant (see Patent Document 1, for example). Moreover, when FeO is used as an oxide colorant, absorption characteristics of the absorber in the near-infrared region become satisfactory. Therefore, it has been known that absorption characteristics of an absorber in the visible light region to the near-infrared region become satisfactory by making the absorber contain FeO and Fe2O3 (see Patent Document 2 and Patent Document 3, for example).    Patent Document 1: Japanese Published Unexamined Patent Application No. H02-38343    Patent Document 2: Japanese Published Unexamined Patent Application No. H09-71436    Patent Document 3: Japanese Published Unexamined Patent Application No. 2003-137595